The present invention relates to a novel system which cooperates with a filter in order to detect and identify particles of conductive or semiconductive materials entrained in a fluid stream.
In the case of many forms of mechanical apparatus, such as heavy machinery, in which lubricant systems are provided to prolong the operating lifetime, it is desirable to monitor the wear of critical parts. Such monitoring permits preventive maintenance to be scheduled in an optimum manner.
It has long been the practice to carry out detailed chemical and physical analyses of oil samples removed from lubrication systems in order to obtain such wear determinations. Such analyses are performed in order to determine the composition and quantity of particles in the oil sample, on the basis of which component wear as a function of operating conditions can be identified and evaluated.
Other techniques which have been recently developed allow for more rapid analyses of lubricant samples. One such method, known as ferrography, can be employed to measure the presence of ferromagnetic particles. This technique involves the use of a permanent magnet on which the particles accumulate and a magnetometer to measure the quantity of particles collected. This technique can be employed under on-line, real time conditions and eliminates the need to collect and analyze separate samples.
Other techniques which have been proposed also involve the use of magnets to collect samples and the provision of a detection circuit which produces an output when the quantity of samples collected completes an electric current path.
All of the techniques described above are limited to the detection and analysis of ferromagnetic particles. This severely limits the applications of such techniques because most sophisticated machinery installations in which real time diagnostics are desirable employ a wide variety of non-ferromagnetic materials.